Quadriceps tendon rupture typically occurs in patients over age 40. It is approximately three times more frequent than patellar tendon rupture in adults in this age group. Patients may be predisposed to ruptures due to calcific tendonitis, fatty degeneration, arthritis, infection, and gout.
Quadriceps tendon rupture can be classified as incomplete or complete. When the tendon has been ruptured for 6 weeks or more, it is considered neglected. It has likely retracted proximally and will be more difficult to treat.
Patients present with acute onset of knee pain, swelling, and substantial weakness and difficulty walking. Occasionally, patients may report an audible pop. Many authors have described patients with increasing suprapatellar knee pain prior to rupture, suggesting a degenerative process leading to rupture.
A palpable defect may be present. Straight leg raise testing will reveal complete inability to extend the knee or extension lag if the extensor mechanism is still intact. If intact, the retinaculum can still allow the patient to extend the knee, even in a complete quadriceps tendon rupture. Ecchymosis and swelling may be present. The patella may be able to be displaced inferiorly. Patella baja may be detectable on lateral knee radiographs, ideally with the knee in 30 degrees of flexion. If the diagnosis is in doubt, MRI or ultrasound can be utilized.
For ruptures treated in a timely manner, a direct repair can be used. Mid-substance tears can be repaired end to end with a large (no. 5), non-absorbable locking stitch. For ruptures at the osteotendinous junction, there may be a small sleeve of tendon remaining. However, this is not sufficient to support an end-to-end repair. Instead, the diseased tendon is debrided off the superior patella, exposing bleeding bone, and the tendon is fixed to the area of debrided bone. Distal fixation of the large, non-absorbable locking stitch should be run through the patella (often through longitudinally oriented drill holes). The drill holes and suture can exit the patella through the anterior cortex to avoid iatrogenic injury to the patellar tendon.
Postoperative treatment includes a cylinder cast worn for 4 to 6 weeks, with advancement of weight-bearing at approximately 3 weeks. Knee bracing with gradual progression of range of motion is then begun. Physical therapy with strengthening is necessary for an optimal outcome.
If the quadriceps is torn, but the extensor mechanism is intact, non-operative treatment is a possibility. Treatment consists of a cylinder cast followed by knee bracing, with gradual increases in range of motion.
- Quadriceps atrophy, extensor lag, decreased passive range of motion, and re-rupture are complications experienced after treatment.
- Infection and wound complications can also result, especially with subcutaneous placement of non-absorbable sutures and with incisions placed directly over the tibial tubercle.
- Patellar tracking can also be affected if malalignment occurs after quad tendon repair.